Photographic emulsion



Patented Jan. 9, 1934 PATENT OFFICE ramasse rno'roGRArmc sMULsIoN Leslie G. S. Brooker, Rochester, N. Y., assigner to Eastman Kodak Company, Rochester, N. Y., a corporation of New York Appiieaaon June 11, reso. seria1No.4so,54

23 Claims.

This invention relates to ,a new composition of matter and particularly to a new class of photographic sensitizing dyes and a method for their preparation.

5 An ordinary photographic emulsionis indifferent as a rule to those colors of the spectrum oi longer wave length and various types of sensitizing dyes have been suggested for incorporating in photographic emulsions or for employing over 1@ the emulsion as an overcoating so as to'increase the 'spectral sensitiveness. Many cyanine dyes have been described for this purpose containing thiazole nuclei, such for instance as those described in my copending applications Serial No.

337,177 led February 2, 1929, matured into Patent 1,846,300 and Nos. 435,104, matured into Patent 1,846,301 and 435,105 filed March l2, 1930. There have been no dyes described however containing the thiazoline nucleus.

vide a process for the preparation of photo-sensitizing dyes containing the thiazoline nucleus.

Another object of this invention is to provide The base itself has the structure -s H2c5/1\ E u 2 -CHn and is usually numbered as'shown in the struc= tural formula. The carbon atom numbered 2 is also called the a carbon atom (Hantrsch, Annalen, 1888, 249, 3) from the initial letter oi the words Mittel or Meso, but herein the numbering as shown above will be used exclusively.

By a thiazoline nucleus is meant a (substituted or unsubstituted) 4,5-dihydrothiazole" nucleus. The name thiazoline has been used to denote this configuration for many years, (see Gabriel & Heymann Ber., 1890, 23, 157; Gabriel, Ber., 1891, 24, 1110; Gabriel si Hirsch, Ber., 1396. 29, 2910; Willsttter & Wirt-i1, Ber., 1909, 42, 1909, 1919). l i

An object of the present invention isto pro-l the linkage between the 4 and 5 carbon atoms being a single bond.

2-methylthiazoline readily forms alkyl quaternary salts such as the methiodide, ethiodide, 7@ alliodide, metho-p-toluenesulfonate, etc., and these compol'mds undergo condensation with, quinoline alkyl Quaternary salts to give risel to dyes for which the name thiazolino-iso-cyanine is proposed, by analogy with the somewhat simi 75 larly constituted thio-iso-cyanines. These new 'dyes may berepresented by the general formula I6' 7' l s s s) R s@ n,cs/1\ Y t 2C=CH 4'3, 2,1' Hz 4 3 l I B as where R' and R2 represent alkyl groups and X an acidic radical. The dye molecule is numbered as shown in the gure so that the general name for a compound of this type is 1-alkyl3alkylf thiazolino-iso-oyanine salt.

The 2-methylthiazoline alkyl quaternary salts also undergo condensation with 2-iodoquinoline alkyl quaternary salts to give dyes which from their method of preparation and analytical re sults are doubtless of the general formula also undergo condensation upon themselves to give rise to products for which the name thiazolinocarbocyanine is proposed, and which are probably represented by' the following formula by analogy with the somewhat similarly constituted bases 1methylbenzothiazole, quinaldine, 2-methyl--naphthothiazole, etc., all of which yield carbocyanine dyes under similar treatment.

H104' l 4 H5 where R' stands'for the substituent group. This type of compound is obtained when a tri alkyl ester of an ortho carboxylic acid other than orthoformic ester is employed in the condensation. For instance trimethyl orthoacetate yields methyl 3 :3' dialwl thiazolinccarbocyanine salt while trimethyl orthoproplonate yields a 'l- 4ethyl-3:3' dialkyl thiazolinocarbocyanine salt.

Lastly, sensitizing dyes are produced by the condensation of 2-methylthiazoline alkyl quater- Aes nary salts with dialkylaminobenzaldehydes such` as p-dimethylaminobenzaldehyde, giving rise to products of the type /s n P v s H Ik erven The nomenclature and numbering of the above classes of compounds and intermediates are in accord with present usage and also the system used in my co-pending applications of Serial Numbers 437,017, led March 19, 1930 and 435,- 104, led March 12, 1930, matured into Patents 1,861,836 and 1,846,301, respectively. The numbering oi.' the thiazoline nucleus already given is preserved whenv that nucleus forms part of a cyanine dye molecule. The numbering, of course, is arbitrary and is given for the guidance of those skilled in organic chemistry in order that there be no question as to the identity o! the compounds covered by my invention.

The diagrammatic spectrograms constituting the accompanying drawing illustrate the regions of the spectrum to which the various types of dyes herein disclosed will sensitize a gelatinesilver-halide emulsion and the extent of the sensitization at various wave lengths. The figures or this drawing and the various types or groups of dyes, the sensitizlng properties of which they illustrate, are as followsspective classes of dyes above illustrated are all comparable to the sensitization illustrated.

I will now give several examples for preparing members of each of the classes of dyes above referred to but it `will be understood that they are merely representative of a great number of methods in which the proportions given and equivalents used may vary in accord with the particular type of dye required. My invention. therefore, will not be restricted thereby except as'indicated in the appended claims.

Preparation of Z-methyl thiazolz'ne alkyl quaternary salts 2-methylthiazoline methiodide was made by heating 30.3 g. (1 mol.) of 2-methylthiazoline under reflux with 44.7 g. (1 mol.}5% excess) of methyl iodide, the latter being added in portions. The initial reaction was rapid but the heating was continued over night on the steam bath. The productwas crystallized from a mixture of acetone and methyl alcohol and colorless crystals were obtained. A rst crop weighed 49.3 g. and n concentrating the mother liquors a seoond crop of 6.6 g. was obtained.

Z-methylthiazoline ethiodide was madesimilarly, the base (30.3 g., 1 mol.) being refluxed with ethyl iodide (49.1 g., 1 mobi-5% excess) over night. The crude product was obtained as colorless needles on recrystallization from a mixture of acetone and methyl alcohol, and a rst crop weighed 37 g. and a second crop, obtained by concentrating the mother liquors, 11.8 g.

Z-methyl thiazoline allz'odz'de Equimolecular proportions of 2-methylthiazoline and allyl iodide were heated together under a reilux condenser for half an hour. Oily drops were formed at first and gradually increased in bulk until the whole was a brown viscous mass.

In Example 5 this crude product was used Without further purication.

2-methylthiazoline 'metilo-p. toluene sulfoiate Approximately eouimclecular proportions ci Z-methylthiazoline and methyl p. toluene sul fonate were heated together for about an hour in an oil bath at 11G-120. (Sometimes a slight excess of the methyl p. toluene sulfonate was employed.) The Quaternary salt solidified to a yellowish mass and was used without further purification.

Z-methyl thsiazolnev eth0-p. toluene sulfonate Approximately equimolecular proportionsj of 2-methylthazoline and ethyl p. toluene sulfunate were heated together overnight or for a longer period in an oil bath at about 10U-110. This crude quaternary salt was likewise used without further purification'. v

'IHIAzoLINo-Iso-CYANINES Example 1 1 :3-dimethylthiazolino-iso-cyanine iodine.- 4.9 g. (1 mol.) of Z-methylthiazoline methiodide and 5.4 g. (1 mol.) of quinoline methiodide were dissolved in 25 cc. boiling absolute ethyl alcohol and 1.3 g. (1 mol.) of 85% solid caustic potash, dissolved in 10 cc. boiling absolute ethyl alcohol, added during five minutes with shaking. The vessel in which the caustic potash had been dissolved was rinsed out with 5 cc. more solvent. The solution darkened and became yellowish-orange and potassium iodide separated. Reuxing was continued for l5 minutes and the solution was allowed to cool, and was finally ltered. The residue was washed with a little cold water to remove inorganic salts and followed by cold acetone. The product was a light yellowish-brown crystalline powder and weighed 1.1 g.

An increased yield of dye, based on the starting weight of the 2methylthiazoline methiodide, was obtained by using the following proportions.

4.9 g. (1 mol.) 2-methythiazoline methiodide was dissolved in 50 cc. absolute ethyl alcohol together with 10.9 g. (2 mols.) of quinoline methiodide and 2.6 g. (2 mols.) of approximately 85% solid caustic potash dissolved in 25 cc. of hot absolute ethyl alcohol added in portions over 5 minutes. After boiling for 15 minutes longer, the solution, which had turned an orange color and from which much solid had separated, was stood to one side to cool. The residue on ltration was washed as in the preceding experiment when a brownish powder was left which, when dried, we'ghed 3.1 g, On crystallizing from methyl alcohol. orange-yellow needles were obtained which gave a yellow solution in methyl alcohol.

Example Z 3 methyl-1'-ethylthiazolino iso cyanine odide-2.4 g. (l mol.) 2-methylthiazoline methiodide was dissolved in l5 cc. boiling absolute ethyl alcohol together with 5.7 g.v (2 mols.) quinoline ethiodide, and the condensation ed'ected by using l g. (1.5 mols.) of approximately solid caustic potash dissolved in 10 cc. of the same solvent and added over five minutes, boiling being contnued for ten minutes more. The product obtained by iiltering the cooled solution was washed with cold water and then with acetone, and on drying weighed 1.4 g.

An improved yield (1.6 g.) was obtained when 1.3 g. (2 mols.) of the caustic potash was employed in place of the l g. 1.5 mols.) used in the foregoing experiment.

On recrystallizing the dye from methyl alcohol, light brown needles were obtained which gave a yellow solutionsin that solvent.

Example 3 Example 4 d1'de.-2.6 g. (1 mol.) Z-methylthiazoline ethiodide and 5.4 g. (2 mols.) quinolinemethiodide were condensed in 15 cc. boiling absolute ethyl alcohol, using 1.3 g. (2 mols.) 85% solid caustic potash dissolved in 10 cc. boiling absolute ethyl alcohol and rinsed out with a further 5 cc. The whole was reuxed for seven minutes and allowed to crystallize, and then filtered and washed as in the foregoing experiments. 1.8 g. of dye remained as a brown crystalline powder. When crystallized from methyl alcohol, brown crystals reilecting green and blueA light were obtained, which gave a yellow solution.

Example 5 1:3diallylthiazolno-iso-cyanine iodide-2 g. (1 mol.) 2-methylthiazoline was heated with 3.4 g. (1 mol.) allyl iodide on a steam bath under a redux condenser for half ain hour. Oily drops were formed at first and gradually increased in bulk until the whole was a brown viscous mass. This crude product was used without further purification. 20 cc. of absolute ethyl alcohol were added, followed by 11.9 g. (2 mols.) of quinoline alliodide and the boiling solution treated with 2.7 g. (2 mols.).A of the 85% solid caustic potash dissolved in a further 2,0 cc. of boiling absolute ethyl alcohol. The whole was boiled for ten minutes and allowed to cool over night and the dye isolated as in the foregoing experiments. 1.2 g. of dye was obtained as brown aggregates of crystals which gave brownish crystals on crystallization from methyl alcohol, in which they gave a yellow solution'.

Example 6 1' :3:6'-t1'imethylthaeolino iso cyanine odz'de.-2.5 g. (1 mol.) Z-methylthiazoline methl iodide treated with 5.7 g. (2 mols.)- S-methylquinoline methiodide, and 1.3 g. (2 mols.) of 85% solid caustic potash gave 1.8 g. of crude dye which crystallized from methyl alcohol in yellow needles, and which gave a yellow solution in that 10 solvent.

Example 7 dye whichl gave light brown needles on twice recrystallizing from acetone.

V THIAzoLINo-a-CYANINES rlhese compounds were made by condensing a 2-methylthiazoline alkyl quaternary salt with a. l 2-iodoquinoline alkyl quaternary salt. using ab- A solute ethyl alcohol as a solvent and caustic potash as the condensing agent. l

Example 8 l 1 :3-dmethylthiazolino-gb-cyanne iodide-2.5 g. (1 mol.) of 2-methylthiazoline methiodide was dissolved in 25 cc. boiling absolute ethyl alcohol in which 4 g. (1 mol.) of finely pulverized 2- iodoquinoline methiodide was suspended. 1.4 g. l (2 mols.) of approximately 85% solid caustic potash was dissolved in`10 cc. of the same solvent, Y boiled, and this solution gradually added to the hot suspension` with vigorous shaking. AV considerable amount of heat wasevolved and the i solution darkened in color through yellow to orange, while much potassium iodide separated. Boiling under reflux was continued over ten minutes and the whole was allowed to cool over night. It was then filtered, washed with alittle colclacetone, followed by cold water and then by Y alittle cold acetone again, when' the dye was obtained as an orange powder which weighed 2.4

g. when dry. It gave a yellow solution in methyl alcohol, from which solvent it` crystallized in orange needles.

Example 9 Example 10 1 :3-diethylthiazolino-o'-cyanne iodide- 2.6 g. (1 mol.) 2-methylthiazoline ethiodide, condensed with 4.1 g. (1 mol.) 2iodoquinoline ethiodide, using 1.4'g. (2 mols.) of the grade of caustic potash used throughoutffurnished 2.4 g. of the dry dye. This was recrystallized twice from methyl alcohol, which treatment removed a red impurity, and the pure dye was obtained in yellowish-orange crystals which gave a yellow das solution in the solvent.

Example 11 1' methyl -3- ethylthiazolino -ocyanine iodide-2.6 g. (1 mol.) 2-methylthiazoline ethiodide was condensed with 4.0 g. (1 mol.) 2-iodoquinoline methiodide, using 1.4 g. (2 mols.) of

Vcaustic potash. 2.7 g. of the dry dye was obtained which gave a yellow solution in methyl alcohol, from which it was recrystallized and obtained in the form of an orange crystalline powder.

THIAzoLmocAaBocYANINEs Example 12 3:3'-dimethylthazolinocarbocyanine iodide.-

3 g. (1 mol.) 2-methylthiazoline was heated i'orone hour in an.oil bath at 11o-120 with 5.6 g. (1 mol.) methyl p-toluenesulfonate. The quaternary salt solidified to a yellowish mass and was used without further purification. It was dissolved in 15 cc. of boiling pyridine and refluxed for five hours with 8.9 g. -(2 mols.) ethyl orthoformate. The*solution rapidly became orange colored. It was treated with a large excess of potassium iodide (40 g.), dissolved in 100 cc. of hot water, and stood aside to crystallize. The solution was filtered and the residue washed with waterfollowed by acetone, and dried. 2.1 g. of

a light brown crystalline powder was obtained which gave a pure yellow solution in methyl alcohol, from which it crystallized in the .form of light brown crystals.

Example 3 3 :3' diethylthazolinocarbocyanine iodide-3 g. l mol.) Z-methylthiazoline was heated over night with. 6 g. (l mol.) ethyl p-toluenesulfonate .at

10o-110. The quaternary salt was used without further purification. It was refluxed for 4.15 hours 4with 8-.9 g. (2 mols.) of ethyl orthoformate. using 12 cc. dry 'pyridine as a solvent, and was then treated with excess (15 g.) of potassium iodide' dissolved in 50 cc. of hot water, and allowed to stand over night. It was necessary to chill and stir the -solution in order to induce crystallization, and then the crystals were filtered off, washed with water followed by acetone, and dried. Weight 3.1 g. of an orange crystalline powder. On crystallizing from methyl alcohol in which .the dye gave a yellow solution, orange-brown needles were obtained showing a blue reflex.

Example 14 3:3".'7-trz'methyl thazolno carbocyanine iodide-4 g. (1 mol.) 2-methyl thiazoline was heated with 7.6 g. (slightly more than 1 mol.) of methyl p.` toluene sulfonate for 1?/2 hours at 110. The quaternary salt solidified and was used without further purification, being refiuxedfor four hours with 20 cc. dry pyridine and 9.6 g. (2 mols.) trimethyl ortho acetate.

At the end of this time a solution of 20 g. potassium iodide in 60 cc. of hot water was added and the whole placed in a freezing mixture and crystallization, which was somewhat difllcult to induce, promoted by stirring with a glass rod. When no more dye appeared to separate the whole was quickly filtered and washed with a little cold water followed by a little cold acetone. The dye was obtained as an orange colored crystalline powder weighing 1.4 g. when dry and could be recrystallized from methyl alcohol in which solvent'it gave a yellow solution.

Example 15 3:3'dimethyl7ethyl thaaolino carbocyam'ne iodide-A similar amount of Z-methyl thiazoline metho p. toluene sulfonate, prepared as in Example14 was refluxed for 41/2 hours with 20 cc. dryl pyridine and 10.8 g. (2 mols.) trimethyl ortho propionate. The reaction mixture was then treated with a hot solution of 20 g. potassium.

iodide in 60 c'c. of water and allowed to crystallize out overnight by standing in the refrigerator. In the morning a further crop of crystals was yobtained by stirring the liquid, while freezing well Example 16 3 :3 :7 -triethyl th'iazolino carbocyanine iodide.- 3 g. (l mol.) 2-methyl thiazoline was condensed overnight with 6.3 g. (rather 'more than 1 mol.)

of ethyl p. toluene sulfonate. The crude quaternary salt was then refluxed for 31,4 hours with 10 cc. dry pyridine and 8.1 g. (2 mols.) trimethyl ortho propionate. The 'reaction mixture was treated with a solution of, 10 g. potassium iodide in 50 cc. water and on standing in the refrigerator for several 'days lcrystals slowly sepa- -rated. Finally the whole was well chilled with occasional stirring for several hours in an icesalt mixture and filtered and washed with a little cold water followed by a little cold acetone. The

Vdye formed an orange crystalline powder and weighed 1.2 g. Avfurther 0.5 g. was obtained by evaporating down the mother liquor in vacuo and washing out the inorganic salt from the residue with a little water and then the organic impurities with ether followed by acetone. The

dye was crystallized from a mixture of methyl alcohol and acetone and gave an orange crystalline powder. The solution was yellow.

STYRYLTHIAZOLINE COMPOUNDS.

to a mass of crystals on transferring to a beaker and stirring, and on cooling it was filtered and washed with acetone. When dry it weighed 4.4 g. It crystallized from methyl alcohol in the form of pinkish-brown needles and in this solvent it gave a yellow-orange solution.

2p. dimethylaminostyrylthiazoline ethiodde.- 5.2 g. (1 mol.) Z-methylthiazoline ethiodide was condensed in 15 cc. boiling methyl alcohol with 3.0 g. (l mol.) p-dimethylaminobenzaldehyde by reuxing for about 16 hours and using a few drops of piperidine-as a catalyst. Most of vthe .methyl alcohol was evaporated ol' and the residue was stirred withether when it solidified. It Was ltered orf and crystallized from a mixture of methyl alcohol and acetone, when 4.0 g. of a i'elted mass of orange needles was obtained. The dye gave a yellow-orange solution in methyl alcohol.

By substituting various similar or dissimilar alkyl groups in the positions in the structural formul occupied by the letters R, R' and R2 many sensitizing dyes may be obtained. The letter X indicates any suitable acid radical such, for example, as the halide's, p-toluene sulfonate, alkylo sulfate or in fact any suitable acid radical Which will not greatly decrease or destroy the sensitizing properties of the dye, this radical being necessary to give electrical neutrality to the molecule. In the claims the phrase-a suitable acid radica -is employed to designate this group of acid radicals.

In the preparation of emulsions containing these photo-sensitizers, it has been found that the dye may be dissolved in methyl alcohol and a Volume of solution containing from 5 to 1GO milligrams of dye added to 1000 cc. of the emulsion. While it may not be necessary to add some of the sensitizers in as large amounts, it may be necessary to add others in amounts larger than those given above; generally about 10 to 20 milligrams of the sensitizing dye is sufcient to obtain the maximum sensitizing effect with a dye having good sensitizing powers. The more powerful dyes, however, may require much less. The regulation or adoption of the most economical proportions will be apparent to those skilled in the art upon observing the sensitizing power of the particular dye for the particular emulsion employed. The above examples are, therefore, illustrative andnot to be understood as limiting the invention in any sense.

It is apparent from a thorough consideration of the above description that any cyanne dye prepared from the base 2-methylthiazoline will come within the scope of this invention whatever may be the radicals indicated in the various structural formul by the letters R, R', R2 and X or for that matter any similar cyanne dye derived -from a 2-methyl thiazoline substituted in one or both of the positions (numbered 4 and 5 in the formula given) available for substitution, together with the employment of such dyes for photographic sensitizing and other purposes.

I claim:

1. A photographic gelatino-silver-halide emulsion containing a cyanne dye which contains a thiazoline nucleus.

2. A photographic vgelatine-silver-halide emulsion containing a cyannedye which contains a thiazoline nucleus and a nitrogen containing nucleus, the nitrogen atoms of the two nuclei being connected by a chain consisting of an uneven number of carbon atoms and the linkages of this chain being conjugated.

3.A A photographic gelatine-silver-halide emulsion containing a dye selected from the group of dyes containing the thiazoline nucleus and consisting of dialkylaminostyrylthiazoline alkyl- Quaternary salts, thiazolino-iso-cyanines, thiazolino-pseudocyanines, thiazolinocarbocyanines and 7alkyl-thiazolinocarbocyanines.

4. A photographic gelatino-silver-halide emulsion containing a dye selected from the group of dyes containing the thiazoline nucleus and `consisting of styrylthiazoline alkylquaternary salts, -thiazolino-iso-cyanines, thiazolino-p'seudocyanines, thiazolinocarbocyanines, and rI-alkylthiazolinocarbocyanines, the nitrogen atoms of which dyes are each linked to an alkyl radical While one nitrogen atom of the dye is also linked to a suitable acid radical.M

'5. A`photographic gelatino-silver-halide emulsion containing a'cyanine dye which contains a thiazoline nucleus and a nitrogen containing heterocyclic nucleus, the nitrogen atoms of the two nuclei being connected by a chain consisting of an uneven number of carbon atoms and the linkages of this chain being conjugated.

6. A photographic gelatino-silver-halide emulsion containing a carbocyanine dye which contains two thiazoline nuclei.

7. A photographic gelatine-silver-halide emulsion containing a carbocyanine dye which contains two thiazoline nuclei linked together by a trimethenyl chain.

8. A photographic gelatino-silver-halide emulsion containing a carbocyanine dye which contains two thiazoline nuclei linked. together by 4a trimethenyl chain, the nitrogen atoms of which are each linked to an alkyl group while one is linked to a suitable acid radical. l

9. A photographic gelatino-silver-halide emulsion containing a 3:3-dialkylthiazolinocarbocyanine salt.

l0. A photographic gelatino-silVer-halide emulsion containing a 3.3-dirnethylthiazolinocarbocyanine iodide.

11. A photographic gelatino-silver-halide emulsion containing a 3 :3'diethylthiazolinocarbocyanine iodide.

12. A photographic gelatino-silver-halide emulsion containing a carbocyanine dye which contains two thiazoline nuclei linked together by a trimethenyl chain, the hydrogen of the central methenyl group of the trirnethenyl chain being substituted by a suitable univalent group.

13. A photographic' gelatino-silver-halide emul-` sion containing a carbocyanine dye which contains two thiazoline nuclei linked together by a trimethenyl chain, the hydrogen of the central methenyl group of the trimethenyl chain being substituted by an alkyl group. Y

14. A photographic gelatino-silver-halide emulsion containing a Ilalkyl-thiazolinocarbocya nine.

15. A photographi gelatine-silver-halide emulsion containing a 3: r'T-trialkylthiazolinocarbocyanne salt.

lil@

16. A photographic gelatino-silver-halide emulsion containing a cyanine dye which contains a thiazoline 'nucleus and a quinoline nucleus, the nitrogen atoms of Ywhich are linked together by a chain of an uneven number of carbon atoms.

17. A photographic gelatino-silver-halide emulsion containing a cyanine dye which contains a thiazoline nucleus and a quinolne nucleus, the nitrogen atoms of which are linked together by a chain of ve carbon atoms.

18. A photographic gelatino-silver-halide emulsion containing a'. 1alkyl3alkylthiazo1inoiso cyanine salt.

19. A photographic gelatino-silver-halide emulsion containing a cyanine dyeiwhich contains a thiazoline nucleus and a quinoline nucleus, the

nitrogen atoms of which are linked together by 20. A photographic gelatina-silver-halide emulsion containing a 1'alkyl3 -alkylthiazolino-pseudo-cyanine salt.

21. A photographic gelatino-silvr-halide emulsion containing a 2-dialkylaminostyrylthiazoline alkyl halide.

22. A photographic gelatino-si1verhalide emulsion containing a dye selected from the group consisting of a 2-o. dimethylannostyrylthiazoline 

